1. Field of the Invention
The present invention relates to a color filter used in a color liquid crystal display device or the like and a method of manufacturing the color filter.
2. Description of the Related Art
A color filter layer is formed on the inner surface of one of opposite glass substrates to prevent degradation of display quality in a conventional liquid crystal display device.
The conventional color filter layer is formed in the following manner. A solution of a hydrophilic resin such as a bichromate-sensitized gelatin, glue, casein or polyvinyl alcohol is applied to the entire surface of a transparent substrate such as a glass plate by spin coating. The resin layer is exposed with light according to mask exposure, thereby obtaining a predetermined pattern. The pattern is then developed to obtain a relief pattern. The relief pattern is dyed with an acidic dye of a desired color. Thereafter, a tannic acid aqueous solution and a tartar emetic aqueous solution are used to perform anti-dyeing. This operation is repeated by the number of colors to prepare a color filter portion. In addition, in order to improve display quality of the liquid crystal display device, a light-shielding black matrix pattern is formed at a boundary of adjacent colors before or after formation of the color filter. The matrix-like light-shielding pattern can be formed in the same manner as in the color filter portion. A relief pattern is formed by a photolithographic technique and is colored with a black dye to obtain the light-shielding pattern.
However, according to a method of forming a conventional color filter layer described above, all the light-shielding layer (black), and red, green, and blue portions are formed by photolithographic techniques. Therefore, the number of manufacturing steps is large, which is undesirable in terms of production efficiency. In addition, if a pinhole is formed in a mask, although very small, it causes an omission in the light-shielding layer or each color portion in an etching step. The omission has a size several times that of the actual pinhole to increase a large number of defective filters. Another problem is that each color is obtained by using an expensive organic dye, and the organic dyes are easily degraded by light or heat. In particular, since the light-shielding layer is dyed in black, a satisfactory light-shielding effect cannot be obtained.